1. Technical Field
The present invention relates to a liquid ejecting head that ejects liquid drops from its nozzle openings, and a liquid ejecting apparatus that is provided with such a liquid ejecting head. More particularly, the present invention relates to an ink-jet recording head that ejects ink drops as one specific example of various kinds of liquid drops, and an ink-jet recording apparatus that is provided with such an ink-jet recording head.
2. Related Art
A typical example of various kinds of liquid ejecting heads is an ink-jet recording head, which is used, for example, in a printer, a facsimile machine, and a copying machine. Some of ink-jet recording heads have a fluid channel formation substrate, which has liquid flow channels having pressure generation chambers (i.e., compartments) each of which constitutes a part of the liquid flow channel and is in communication with a nozzle opening, and piezoelectric elements, which are provided over one surface of the fluid channel formation substrate, specifically, at regions opposed to the pressure generation chambers with a diaphragm (i.e., vibrating plate) interposed therebetween. For example, according to the configuration described in JP-A-2005-153243, a fluid channel formation substrate has pressure generation chambers, a communication portion (i.e., space) that retains (i.e., reservoirs) ink to be supplied to each of the pressure generation chambers, ink supply passages and communication passages through which the communicating portion is in communication with each of the pressure generation chambers. With such a configuration, piezoelectric elements are “voltage-deflected” to cause the deformation of a diaphragm, which results in expansion/contraction of the inner capacity of the pressure generation chambers. By this means, ink is supplied from the communication portion to the pressure generation chambers via the communication passages and the ink supply passages; and ink drops are ejected from nozzle orifices (i.e., holes).
In the configuration of related art, there is a problem in that “air bubble entrainment (drift of air bubbles)” could occur at the boundaries between the communicating portion and separate flow channels, each of which is demarcated by partition walls and is made up of a pressure generation chamber and fluid passages. That is, such a phenomenon could occur at each boundary between the communication passage and the communication portion. In a typical configuration of related art, the tip surface of each partition wall at the communication-portion side is formed as a flat surface that is either substantially/approximately perpendicular or slanted with respect to the surface of fluid channel formation substrate. For this reason, it is possible that air bubbles that are entrained in ink collide against the tip surface of the partition wall. As a result of such a collision, the air bubbles entrained in ink could drift and thus remain at, for example, a corner portion that is formed by the partition wall and a diaphragm (i.e., elastic membrane). Then, the growth of the air bubbles that remain at the corner portion adversely affects ink-drop-ejecting characteristics of the related-art configuration, causing a problem such as missing dots, a decrease in ejection amount, or the like.
Needless to say, the same problem occurs in liquid ejecting heads that eject various kinds of liquids other than ink drops.